This invention relates to simultaneous time resolution and wavelength determination of a light beam.
Determination of the spectral characteristics of a light beam, particularly for visible light, has been performed for several centuries. Determination of temporal characteristics of a light beam has been possible more recently, with development of fast response light beam analyzers that can analyze beams over time intervals having durations of the order of nanoseconds (nsec) or less. Until recently, no serious need existed to analyze and provide simultaneous information on spectral and temporal characteristics of a light beam over closely spaced time intervals. Existing spectral measurement devices will provide a measurement of the spectral content of a light beam, accumulated over a time interval with a duration of the order of seconds to minutes; and a temporal measurement device will provide an aggregated measurement of light energy over a band of wavelengths for a time interval of the order of sub-nanoseconds (xcexcsec) to milliseconds (msec), but with no cooperative action.
What is needed is a system that rapidly, simultaneously and accurately determines both spectral and temporal characteristics for a laser beam or other narrow light beam, for individual wavelengths spaced apart by small wavelength increments (e.g., xcex94xcex≈0.01-10 nm) over a wavelength range of the order of hundreds of nm and over a measurement time interval of the order of sub-milliseconds.
These needs are met by the present invention, which provides a system and method for simultaneously measuring and providing readings for intensity and wavelength(s) of a light beam and the time interval during which such wavelength(s) was present. The system can track changes in light beam intensity and/or wavelength(s) over a sequence of non-overlapping time intervals, each of length 10-1000 xcexcsec, or over larger time intervals if desired. The system separates wavelength or spectral distribution in a light beam (oriented in a first direction) from temporal distribution (oriented in a second direction) and repeats this separation at time intervals that are spaced apart by 10-1000 nsec.